Layered clay minerals such as montmorillonite are composed of silicate layers with a thickness of about 1 nanometer. Dispersions of such layered materials in polymers are frequently referred to as nanocomposites.
Recently, there has been considerable interest in forming nanocomposites as a means to improve the mechanical properties of polymers. Incorporating clay minerals in a polymer matrix, however, does not always result in markedly improved mechanical properties of the polymer. This may be due to the lack of affinity between the layered silicate materials and the organic polymers. Thus it has been proposed to use ionic interactions as a means of incorporating clay minerals in a polymer. In this regard, see for example U.S. Pat. No. 4,889,885 and U.S. Pat. No. 4,810,734. This type of approach, unfortunately, has limited usefulness. Indeed, a more direct, simple, and economic approach to preparing nanocomposites is highly desirable.
One object of the present invention is to provide a latex comprising a layered silicate intercalated with a polymer.
Another object of the present invention is to provide a composite material formed from a latex of a layered silicate and a polymer which material has reduced permeability to small molecules such as air, and improved mechanical properties.
These and other objects, features and advantages of the present invention will become more apparent from the description which follows.